Genetic Factors Associated with Periodontal Disease
According to Carranza there is evidence that indicates that aggressive periodontal disease can be linked to families by a genetic susceptibility. Chronic periodontitis can occur in patients who have a composite genotype that affects interleukin 1, which can result in an increase in the production of interleukin 1. Specific syndromes that include periodontal disease are associated with the parents genetic profile, such as Papillon-Lefevre syndrome, hypophosphatais, and leukocyte function abnoemalities. In addition genetic make-up can also affect a patients response to periodontal therapy.

The genotype is the genetic component of an organism while the phenotype is the characteristic or trait of the organism. Diseases or traits can be monogenic, meaning caused by a single gene, oroliogenic, caused by several genes or polygenic, caused by many genes. Most diseases are multifactorial, in which the etiology is based on genetic and environmental factors. Loci are specific location on chromosomes. Alleles are variations in the nucleotide sequence of the locus. Carranza mentioned studies that conducted in twins that have shown that genetic factors influence clinical measures of gingivitis, probing pocket depth, attahment loss, and interproximal bone height.

Aggressive Periodontal Diseases
According to Bryan S. Michalowicz and Bruce L. Pihlstrom, periodontitis susceptibility alleles are difficult to search for, for two reasons "(1) multiple causes (both genetic and nongenetic) may exist for the same disease (etiologic and herogeneity) and (2) different genetic mechanisms may lead to the same clinical endpoint (genetic heterogeneity)" (Caranza, 2006). In addition, the search for tor susceptible genes has been difficult because of the variations of the disease and the limited criteria for diagnosing the disease.

In studies in the history of periodontitis Loe et al. found that amoing individuals with poor oral hygiene and no access to dental care, some developed disease at a rapid rate. whereas pthers experienced little or no disease.. If one considers this there are genetic variation that some individuals have that make them more susceptible to disease. There are certain markers that have been found listed below that can cause certain defects.
The following tabe contains Gentic and Inherited Disorders Associated with Aggressive Periodontitis:
Disorder
Protein or Tissue Defect
Leukkocyte adhesion
deficiency type I
CD18 (β-2 integrin chain of LFA molecule
Leukkocyte adhesion
deficiency type II
CD15 (neutrophil ligand for E and P selections);
inboarn error in fucose metabolism
Acatalasia
Catalase enzyme
Chronic and cyclic
neutropenias
Unknown
Chediak-Higashi syndrome
Abnormal transport of vesicles to and from neutrophil
lysosomes caused by mutations in lysosomal
trafficking regulator gene
Ehler-Danlos syndrome
(EDS types IV and VIII)
Type III collagen for EDS type IV,
unknown for EDS type VIII
Papillion-Lefevre syndrome
Cathepsin C (dipeptidyl aminopeptidase I)
Hypophosphatasia
Tissue-nonspecific alkaline phosphatase
Trisomy 21
Multiple; critical trisomic region at least 5 Mb long
Prepubertal periodontitis
(nonsyndromic)
Cathepsin C
Kindler syndrome
Defect in actin-extracellular matrix linkage caused by
loss of function mutations in KIND-1

Chronic Periodontal Diseases
The susceptibilty to periodontitis varies for differnet ethnicities and races. These differences may be a result of environmental factors as well as factors related to the genetic make up among different ethnic groups. It may because the different make up of different races. Genetic correlation has been seen to be greater between mother and offspring than father and offspring. Sibling correlation was low.

Genetic testing
Completing genetic testing could be very useful in order to identify patients that are more likely to develop periodontal disease. Genetic testing can detect early forms of periodontitis and then be able to prevent the colonizing of microorganisms in the oral cavity which may help in the preventing disease. The information that is gained from genetic testing can be used in order to predict the outcome of the treatment that is provided.

Hypophosphosphatasia:
Cause by a mutation in the tissue nonspecific alkaline phosphatase gene (1p36.1-p34). This gene alters the how bone is mineralized. Bone, enamel, dentin, cementum are all affected. The fatality of this disease is dependent on the dominance of the gene. Severe cases usually lead to death at an early age. Mild forms of the disease can can lead to loss of permenant dentition. Clinically it may be seen in children with dentinogenesis imperfecta and can be determine by lab work to determine hypophosphophatasia

Papillon-Lefevre:
Is a rare autosomal recessive disorder meaning that both must carry the autosomal genes for the syndrome to appear in the child. It can effect 1 to 4 cases per 1 million. It is characterized by palmoplantar hyperkeratosis and aggressive periodontitis. Both primary and secondary dentitions can be affected. The primary dention is usually lost by 5-6 years of age.Usually by age 15 This syndrome is caused by mutations in the cathepsin C gene, which is located on chromosome 11. Cathepsin C appears to play a role in degrading proteins and activating proenzymes in immune and inflammatory cells. PLS patients that lack all cathepsin C activity, are either homozygotes or compound heterozygotes. Some patients with PLS, AP disease is associated with the virulent microorganism A.a.

The pictures below are from a 15 year old boy with PLS:(http://dermatology.cdlib.org/101/case_reports/papillon/khachemoune.html)
PLS1.jpg PLS2.jpg

References:
Carranza, F. A., Klokkevold, P. R. Newman, M. G., Takei, H. H. (2006). Carranza's clinical periodontology 10th edition. St. Louis, MO: Saunders Elevier.

Wilkins, E. (2005). The clinical practice of dental hygiene, 9th ed. Baltimore, MD. Lipincott Williams and Wilkins.

Down Syndrome:
Down Syndrome is a gentic disorder caused by a chromosomal abnormality in which three rather than two copies of chromosome 21 are made. The prevalence of periodontal disease in Down syndrome is high occuring in almost 100% of patients younger than 30 years of age. Patients with Down syndrome demonstate an increase of periodontal breakdown due to the plaque when compared to similar plaque levels on other patients. The high prevalence and increased severity of periodontal destruction associated with Down syndrome is most likely explained by poor PMN chemotaxis and phagocytosis. Increased numbers of P. intermedia have also been reported in children with Down syndrome.
(Carranza, Klokkevold, Newman, & Takei 2006)
DownSyndrome.gif
Genetic testing in the future
  • As research continues, researchers are able to determine the genetic role in periodontitis as well as the environmental role
  • Once the specific factor is found genetic testing will become used frequently as a preventative measure